Editing Seleucus I Nicator (section)

===Defeat of Demetrius and Lysimachus===
[[File:Démétrios Ier Poliorcète (pièce).jpg|thumb|275x275px|Silver coin of Demetrius I Poliorcetes, with the Greek legend: ΒΑΣΙΛΕΩΣ ΔΗΜΗΤΡΙΟΥ, ''Basileōs Dēmētriou,'' "of king Demetrius".]]
Seleucus nominated his son [[Antiochus I]] as his co-ruler and viceroy of the eastern provinces in 292 BC, the vast extent of the empire seeming to require a double government.<ref name=EB1911/> In 294 BC Stratonice married her stepson [[Antiochus I Soter|Antiochus]]. Seleucus reportedly instigated the marriage after discovering that his son was in danger of dying of love sickness.<ref>http://virtualreligion.net/iho/antiochus_1.html [[Antiochus I Soter]] entry in historical sourcebook by Mahlon H. Smith</ref> Seleucus was thus able to get Stratonice out of the way, as her father Demetrius had now become king of Macedonia.

The alliance between Seleucus and Demetrius ended in 294 BC when Seleucus conquered [[Cilicia]]. Demetrius invaded and easily conquered Cilicia in 286 BC, which meant that Demetrius was now threatening the most important regions of Seleucus' empire in Syria. Demetrius' troops, however, were tired and had not received their payment. Seleucus, on the other hand, was known as a cunning and rich leader who had earned the adoration of his soldiers. Seleucus blocked the roads leading south from Cilicia and urged Demetrius' troops to join his side. Simultaneously he tried to evade battle with Demetrius. Finally, Seleucus addressed Demetrius personally. He showed himself in front of the soldiers and removed his helmet, revealing his identity. Demetrius' troops now started to abandon their leader ''en masse''. Demetrius was finally imprisoned in Apameia and died a few years later in captivity.<ref name="Grainger97-55" />

Lysimachus and Ptolemy had supported Seleucus against Demetrius, but after the latter's defeat the alliance started to break apart. Lysimachus ruled Macedonia, [[Thracia]] and [[Asia Minor]]. He also had problems with his family. Lysimachus executed his son [[Agathocles (son of Lysimachus)|Agathocles]], whose wife [[Lysandra]] escaped to Babylon to Seleucus.<ref name="Grainger97-55" />

The unpopularity of Lysimachus after the murder of [[Agathocles (son of Lysimachus)|Agathocles]] gave Seleucus an opportunity to remove his last rival. His intervention in the west was solicited by [[Ptolemy Keraunos]], who, on the accession to the Egyptian throne of his brother [[Ptolemy II of Egypt|Ptolemy II]] (285 BC), had at first taken refuge with Lysimachus and then with Seleucus.<ref name=EB1911/> Seleucus then invaded Asia Minor and defeated his rival in the [[Battle of Corupedium]] in [[Lydia]], 281 BC. Lysimachus fell in battle. In addition, Ptolemy had died a few years earlier. Seleucus was thus now the only living contemporary of Alexander.<ref name="Grainger97-55" />